What parameters are needed for Nokia 3100 in order to be able to send SMS?
I am getting timeout. Gnokii works.

[GSM1] device = /dev/ttyUSB0 incoming = no baudrate = 19200 check_network = 0 hangup_incoming_call = yes

2016-09-22 13:05:01,5, GSM1: Modem handler 0 has started. PID: 1684. Will only send messages. 2016-09-22 13:05:01,6, GSM1: Checking if modem is ready 2016-09-22 13:05:01,7, GSM1: -> AT 2016-09-22 13:05:01,7, GSM1: Command is sent, waiting for the answer 2016-09-22 13:05:06,7, GSM1: put_command expected (OK)|(ERROR), timeout occurred. 1. 2016-09-22 13:05:06,7, GSM1: <- 2016-09-22 13:05:06,7, GSM1: -> . 2016-09-22 13:05:06,7, GSM1: Command is sent, waiting for the answer 2016-09-22 13:05:11,7, GSM1: put_command expected (OK)|(ERROR), timeout occurred. 2. 2016-09-22 13:05:11,7, GSM1: <- 2016-09-22 13:05:11,7, GSM1: -> AT 2016-09-22 13:05:11,7, GSM1: Command is sent, waiting for the answer 2016-09-22 13:05:16,7, GSM1: put_command expected (OK)|(ERROR), timeout occurred. 3 ... 2016-09-22 13:07:03,3, GSM1: Modem is not ready to answer commands (Timeouts: 0) 2016-09-22 13:07:03,2, GSM1: Failed to initialize modem GSM1. Stopping.

Gnokii works perfectly, check it out:

port = /dev/ttyUSB0 model = 6510 connection = dku5

Connecting Serial device: opening device /dev/ttyUSB0 Serial device: setting RTS to low and DTR to low Serial device: setting RTS to high and DTR to high Serial device: setting speed to 19200 Switching to FBUS mode Serial device: setting speed to 115200 Getting model... Message sent: 0x1b / 0x0006 00 01 00 07 01 00 | [Received Ack of type 1b, seq: 0] [Sending Ack of type 1b, seq: 0] Message received: 0x1b / 0x0032 01 31 00 08 00 01 58 2c 00 26 56 20 30 34 2e 30 | 1 X, &V 04.0 31 20 20 20 20 20 0a 31 36 2d 31 30 2d 30 33 0a | 1 16-10-03 52 48 2d 31 39 0a 28 63 29 20 4e 4d 50 0a 44 00 | RH-19 (c) NMP D 00 00 | Received message type 1b model length: 5 Received model RH-19 Found model "RH-19" Message sent: 0x02 / 0x0006 00 01 00 14 01 00 | [Received Ack of type 02, seq: 1] [Sending Ack of type 02, seq: 1] Message received: 0x02 / 0x0022 01 5b 00 15 00 01 0b 1c 01 f5 00 00 55 02 82 0c | [ U 02 08 07 91 24 91 30 33 03 00 81 08 02 00 00 00 | $ 03 00 00 | Received message type 02 Frame of type 0x02 (SMS handling) received! SMSC Received =====> ENTER gn_sms_send() enc_chars: 22 ext_chars: 0 total: 20 size of the input string: 22 bytes number of characters in the input string: 22 chars =====> ENTER sms_send_single() General Data Coding Default Alphabet size: 20 offset: 0 encoded size: 20 rawsms length: 22 rawsms user data length: 20 dcs: 0x00 Length: 0x16 user_data_length: 0x14 ValidityIndicator: 2 user_data: 5474710E4ACF416110BD3CA733DAE5FA3C7CEE03 Input is 22 bytes long SMS is 20 octets long Sending Sending SMS...(70) Message sent: 0x02 / 0x0046 00 01 00 02 00 00 00 55 55 01 02 3c 11 00 00 00 | UU < 00 04 82 0c 01 08 0c 91 24 91 51 57 62 61 82 0c | $ QWba 02 08 07 91 24 91 30 33 03 00 80 18 14 16 54 74 | $ 03 Tt 7a 0e 4a cf 41 61 10 bd 3c a7 83 da e5 f9 3c 7c | z J Aa < <| 2e 03 08 04 01 a9 | . [Received Ack of type 02, seq: 2] [Sending Ack of type 02, seq: 2] Message received: 0x02 / 0x001e 01 5b 00 03 00 01 0c 18 00 00 5d 55 55 01 07 10 | [ ]UU 01 61 90 22 02 13 45 80 00 01 09 04 01 00 | a " E Received message type 02 Frame of type 0x02 (SMS handling) received! SMS sent (reference: 93) Send succeeded with reference 93! Serial device: closing device

Gnokii plays with RTS and DTR lines, talks about FBUS mode and changes baudrate to 115200. You could try 115200 with smsd, but I think that it is not enough. As there is also some acknowledges handled, likely relating with the mentioned FBUS mode, smsd will not work with this interface.